Lauren Kaplan - Nov 06, 2016

Considerations for Choosing Your Cover Crop

Buckwheat cover crop at University of California Santa Cruz Center for Agroecology & Sustainable Food Systems

For farmers that follow sustainable and organic farming methods, cover cropping is a common practice, with many great ecological benefits.

Cover crops can literally cover the soil, serving as a mulch whether living or dead. They can also be incorporated into the soil as either a nitrogenous “green” manure, or as more mature, carbonaceous addition. Including cover crops in your rotation will improve soil fertility and tilth by adding organic matter (which also increases the water-holding capacity of your soil), breaking up clods, and fracturing compaction from tillage. Cover crops prevent erosion, suppress weeds, and provide habitat for beneficial insects, and allow you to fix (or add) nitrogen and mine or scavenge nutrients for your next cash crop. Some cover crops can double as cash crops or forage for livestock.

There are a wide variety of cover crops out there, all of which provide at least a couple of the benefits listed above. Any cover crop you can work into your crop planning is generally better than none at all, and jumping in with whatever your neighbors or trusted fellow farmers are using isn’t a bad place to start. But by putting careful consideration into which cover crops you use, you can target and maximize your benefits, and really put that cover crop to work for your farms’ specific needs.

Here are some questions to consider when choosing a cover crop or cover crop mix:

What do I most want my cover crop to accomplish?
Primary goals could be the prevention of erosion, scavenging or fixing of nitrogen, suppression of weeds, or improving soil tilth. Which one or two of these are most important, and for which fields?

What are the windows in my cash crop schedule where I could work in cover crops?
When do you anticipate harvesting your cash crops, and when you anticipate those fields to be available for a cover crop? Consider also when and what you plan to plant there the following season, and what that means for you in terms of being able to get into the fields to incorporate or mow, especially if a wet spring could be a limiting factor.

Are there any other considerations, requirements or limitations to consider?
If you are growing in an area that suffers from drought, you might look for a crop that does not require summer water. Or, the type of equipment you have access to might limit your ability to mow or incorporate more carbonaceous, mature cover crop. If you are growing strips of cover crop alongside cash crops, consider height and shading, and the timing for the incorporation of your cover crop with the harvest of your cash crop.

Identifying your primary goals and your window(s) will significantly narrow your options for the best cover crops.

For example, let’s say you are growing in an area with dry summers and heavy winter rains, and your number one struggle is with nutrient losses and poor soil quality caused by erosion. In this case, one of your primary goals may be to establish a dense stand of cover crop in the fall, before winter rains set in, to minimize erosion. A secondary goal may be to add organic matter to improve your soil’s ability to retain water.

There are many crops that are excellent at both preventing erosion and adding organic matter, including annual ryegrass, sorghum-sudangrass, cereal rye and barley to a variety of legumes from cowpeas to clover. To significantly narrow this long list of potentially appropriate cover crops, consider your field schedule.

Your window for cover cropping opens following a harvest of spring broccoli. This leaves you with a lot of options, from erosion-controlling crops that can be seeded in the heat of summer, like a sorghum-sudangrass hybrid, to anything that can be sown in the cooler temperatures of fall, such as an annual ryegrass, oats or barley. Because you’ll be following broccoli, you may want to stay away from brassicas for pest reasons.

If you have a long window, and won’t be planting into the field until early summer, you may opt for something that can overwinter and provide a burst of biomass in the spring. A combination of rye and hairy vetch would give you vigorous spring growth, serving as a green manure for your early summer crop and accomplishing your secondary goal of adding organic matter. If, however, your window closes early (perhaps you’ll be planting an early spring crop the following season, and will need to get into the fields quickly), you may want to go with something like the frost-sensitive sorghum-sudangrass or oats, which will winterkill in lower hardiness zones – something that won’t get away from you in the spring.

Are there any other factors to consider? How well can the cover crops you’re thinking about using establish themselves in the drier months before the rains come? Do you have the water to irrigate them in? Sorghum-sudangrass is very drought tolerant, whereas annual ryegrass is not (but is tolerant of excessive moisture). Perhaps the best option is to plant the sorghum-sudangrass immediately following your spring brassica crop to capture the soil moisture, scavenge nitrogen and improve your soil structure, then till it in and plant the annual ryegrass/vetch mix later in the fall. (As an added benefit, hairy vetch attracts beneficials such as predatory and parasitoid wasps and lady beetles.)

For more on selecting the best crops for your farm, I highly recommend Managing Cover Crops Profitably: an excellent and comprehensive resource available for free online on the Sustainable Agriculture Research and Education (SARE) website. In selecting a list of suitable crops to meet your needs, you may find it helpful to consult a cover crop comparison chart. Charts are available online from sources such as Peaceful Valley and Johnny’s Selected Seeds. For more detail on some of these crops, check out the plant guides offered by the NRCS. For regionally-specific resources (such as this one for growers in Oregon and Washington), look to your local seed suppliers, ag extension offices, or simply to any neighboring farmers growing comparable crops.


Managing Cover Crop Profitably (SARE)
The comprehensive manual on cover cropping from the Sustainable Agriculture Network, complete with helpful charts of top regional cover crop species, an overview of legume and non-legume cover crops, and profiles of specific crops.

Cover Crops and Soil Health (NRCS): Cover Crop Plant Guides
A series of plant guides to describe the characteristics of eleven of the most commonly used cover crops.

Crop Plant Guides

Cover Crop Resources and Seed Vendors for Oregon and Washington (USDA/NRCS):
A guide to regional and national sources for cover crop seed vendors and a diverse list of cover crop-related resources.

Johnny’s Selected Seeds: Farm Seed Comparison Chart

Peaceful Valley: Cover Crop Comparison Chart

If you liked this article, and want to see more like it, enter your email in the subscribe box to the top-right of this page and we'll send you new blog articles as we publish them.

After graduating from UCSC's Center for Agroecology and Sustainable Food Systems, Lauren Alexandra Kaplan spent a season at an organic CSA farm in California before returning east to farm in the Hudson Valley. Prior to pursuing farming full time, she worked in book publishing and helped to launch an urban farm in NYC. Alexandra is an avid salsa dancer and maker of jams, pickles, and kraut.


lou desena

Dec 5, 2016 at 4:11 PM

enjoy you information and resources-

Bunny Goodwin

Dec 7, 2016 at 5:38 PM

What cover crops do you recommend for raised beds in a school garden?


Dec 19, 2016 at 5:10 PM

Hi Bunny! Buckwheat is a nice summer cover crop with a quick turn-around time, and easy to incorporate into the soil. If you an do any cover cropping during the school season, try planting a grass and a legume together for a winter cover crop, and incorporating with students in the spring.

Powered by Tend™